Phoenix is the culprit, Edgeworth is the accomplice. The theory remains mostly the same compared to my previous Phoenix/Edgeworth one.
I'll copy this paragraph from it:
Edgeworth's testimony, while accurate, contains several omissions. In the dining room, he let Franziska out and locked the door again (Franziska went to right bathroom as in previous theories). After that he went into the library, and back into dining room, where he found Larry. Larry hit Edgeworth with the bottle, knocking him out. This bottle shattered, which was the sound Alfred and Payne heard (thinking it came from the study was a mistake). Larry then carried Edgeworth to the library.
Klavier was barricaded by Phoenix beforehand.
What's slightly different: at the same time Larry was transporting Edgeworth into library, Phoenix ran through the central hallway into right hallway and met him there. It was an opportunity for Phoenix to give Larry the wine cellar key, who placed it on Edgeworth (I don't know what sort of collaboration was going on between Larry and Phoenix, but let's say Larry didn't know about murders that were going to occur, or about Payne locked room that was going to happen). This way Edgeworth's testimony remains accurate.
Phoenix kills Franziska, quickly runs back, waits for Payne to open the barricade, knocks him out and moves him to the cellar. Then he kills Larry.
Edgeworth wakes up and both Phoenix and Edgeworth stand near central hallway on both sides, and Edgeworth throws the wine cellar key to Phoenix.
Alfred's testimony doesn't confirm that he was guarding the central hallway the entire time, so it's possible that he entered Entrance area for whatever reason, and couldn't witness this.
Phoenix then used the wine cellar key to move Payne to the study and lock the door.